Render displays solid view objects
What is happening is that material shading, by default, uses a pre-supplied HDRi image as the world (that is why you see some trees and blue skies reflected on the glossy surfaces).
Rendered shading uses the actual settings for the scene, by default just a flat color.
You can set material view to use the actual scene lights and world.

Or you can set an HDRi to be used as environment texture on the world and that would be used for rendered view and to render the scene as well.